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ATLANTA -- More than a fifth of patients with multiple myeloma died of infection within a year of diagnosis, Swedish investigators reported here.

Within a year of diagnosis, 22% of myeloma patients had died of infection-related causes.

Overall, patients with myeloma had an infection risk seven times higher than that of a control group. During the first year after diagnosis, the risk was almost 12 times greater.

The high risk pertained to both bacterial and viral infections, Cecilie Blimark, MD, reported at the American Society of Hematology meeting.

"We found that bacterial and viral infections represent a major threat to myeloma patients," said Blimark, of Sahlgrenska University Hospital in Gothenberg. "We found the risk of specific infections, such as pneumonia and septicemia to be more than 10 times higher in patients than in controls during the first year after diagnosis of multiple myeloma."

The infection rate doubled between the earliest and latest years included in the analysis, which spanned 1988 to 2004.

In light of the findings, the infection risk associated with myeloma therapies requires careful evaluation, as do potential strategies to reduce patients' infection risk, Blimark added.

Infection is recognized as a major contributor to morbidity and mortality in patients with multiple myeloma. The magnitude of infection risk and its consequences had not been examined in a large population-based studies. Blimark and colleagues undertook such a study in an effort to describe and quantify the problem.

Investigators reviewed data for 9,610 patients with multiple myeloma identified in the Swedish national cancer registry for the years 1988 to 2004. The registry had follow-up data to 2007. Each patient was matched by age, sex, and county of residence with four individuals without myeloma, resulting in a control group of 37,718 people.

Using a national patient information registry, Blimark and colleagues abstracted data about the types of infection and dates of occurrence for patients and the control group. Myeloma patients and members of the control group had a median age of 72.

The analysis showed that patients with myeloma had an infection hazard ratio of 7.1 versus the control group (95% CI 6.8 to 7.4). The overall risk difference included a sevenfold higher risk of bacterial infections and nine-fold higher risk of viral infections.

During the first year after myeloma diagnosis, the patients had an infection hazard of 11.6 compared with the control group (95% CI 10.6 to 12.7). The overall infection risk in the first year after diagnosis included a hazard ratio of 11.0 for bacterial infections (95% CI 10.7 to 12.9) and 18.0 for viral infections (95% CI 13.5 to 24.4).

Evaluation of specific types of infections showed that myeloma patients, compared with the control group, had a significantly higher risk (P<0.05) of:

• Septicemia -- HR 15.6
• Meningitis -- HR 16.6
• Cellulitis -- HR 3.0
• Osteomyelitis -- HR 3.5
• Endocarditis -- 5.3
• Bacterial pneumonia -- HR 7.7
• Pyelonephritis -- HR 2.9
• Viral influenza -- 6.1
• Herpes zoster -- 14.8

The analysis also showed that infection risk among myeloma patients has increased in recent years. As compared with 1986 to 1993, infection risk was 1.6 times higher during 1994 to 1999, and had doubled by 2000 to 2004.

Whether the infection risk relates to use of novel drugs needs to be determined, Blimark said. Regardless of cause, clinical trials of prophylactic measures are needed.

In the discussion that followed her presentation, members of the audience credited Blimark and her colleagues with bringing a vastly underappreciated issue in myeloma care to the attention of specialists in the field. They seconded her call for studies to determine the reasons for the growing infection threat among myeloma patients and the need for effective prophylaxis.

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